Prior to the development of pre-hung door assemblies, door assemblies in home and commercial construction and reconstruction were constructed at the job site, in the respective doorways. That is, the individual elements comprising the assembly were received at the job site and the door assembly was completely constructed at the job site.
Thereafter, beginning in the late 1950's and early 1960's, the use of pre-hung door assemblies became prevalent. Pre-hung door assemblies are doors and jambs which are assembled in the factory (i.e. the jambs are attached and the door is attached to the assembled jambs) and shipped to retail outlets through distribution channels as complete units or assemblies. Such pre-hung doors assemblies are then installed in the framing forming the doorways. The casing or molding is attached to the jambs on the job site after the pre-hung door assemblies are affixed to the framing.
The development of such pre-hung door assemblies was an advance in building construction technology and provided many benefits over the prior method of constructing door assemblies entirely at the job site. Among these benefits are that, due to the fact that the pre-hung door assemblies are constructed at a manufacturing site by persons who become skilled at the task, the pre-hung door units are generally of higher quality and are consistently of the same dimensions. In addition, the use of such pre-hung door assemblies decreases the labor time on the job site. Moreover, such pre-hung door assemblies can be installed by almost all workers, as the installation does not require a person of great skill and experience.
However, even when employing these pre-hung door assemblies, the casing must still be properly positioned on and attached to the respective door jambs after the pre-hung door assemblies are installed at the job site. This task requires skilled labor and is time consuming. Thus, while the use of pre-hung door assemblies including the jambs and the doors solve some problems in the field, problems remain in attaching the casing once the pre-hung door assemblies are installed.
One solution to this problem is to manually attach the casing in the factory. However, this is a time consuming process in the factory and increases the cost of the pre-hung door assemblies since the factory normally employs workers of a higher skill and compensation level than in the field. Furthermore, consistency is still a problem since the quality of the attachment is dependant on the skill level and performance of the person performing the task. Further, there is some risk of injury during this manual attachment.
Thus, there is a need for a machine and a method for semi-automatically attaching casing to pre-hung door assemblies. Such a machine and method may have applications beyond pre-hung door assemblies, and may be employed to attach molding or casing to other structural frame elements.
There is one known prior patent which discloses a machine for automatically nailing trim on door jambs, see U.S. Pat. No. 2,830,294 issued to Guerrant on Apr. 15, 1958. However, the machine disclosed in this patent is cumbersome and inefficient.
There are other patents which disclose machines and methods for assembling pre-hung doors with casing, see U.S. Pat. No. 3,015,348 issued to Zern on Jan. 2, 1962, U.S. Pat. No. 3,252,642 issued to Page on May 24, 1966 and U.S. Pat. No. 3,707,256 issued to Lubin on Dec. 26, 1972. The machines disclosed in these patents are also unduly cumbersome and inefficient.
Other known patents disclose machines and methods for automatically or semi-automatically assembling structural frame units, see U.S. Pat. No. 2,903,699 issued to Mazzola on Sep. 15, 1959, U.S. Pat. No. 2,936,457 issued to Chafin et al. on May 17, 1960, U.S. Pat. No. 3,261,527 issued to Sterner on Jul. 19, 1966, U.S. Pat. No. 3,278,177 issued to Zern on Oct. 11, 1966, U.S. Pat. No. 3,431,619 issued to Bowers, Jr. on Mar. 11, 1969, U.S. Pat. No. 3,628,714 issued to Offenwanger on Dec. 21, 1971, U.S. Pat. No. 3,672,554 issued to Smith on Jun. 27, 1972, U.S. Pat. No. 3,681,842 issued to Blakeslee on Aug. 8, 1972, U.S. Pat. No. 3,733,020 issued to Ingram on May 15, 1973, U.S. Pat. No. 3,822,815 issued to Davis on Jul. 9, 1974, U.S. Pat. No. 3,873,015 issued to Whitaker on Mar. 25, 1975, U.S. Pat. No. 4,039,112 issued to Schultz on Aug. 2, 1977, U.S. Pat. No. 4,126,259 issued to Galer et al on Nov. 21, 1978, U.S. Pat. No. 4,127,226 issued to Jasper on Nov. 28, 1978, U.S. Pat. No. 4,254,895 issued to Cheak on Mar. 10, 1981, U.S. Pat. No. 4,258,873 issued to Vela on Mar. 31, 1981, U.S. Pat. No. 4,305,538 issued to Schultz et al. on Dec. 15, 1981, U.S. Pat. No. 4,330,921 issued to White, Jr. on May 25, 1982, U.S. Pat. No. 4,392,599 issued to Russell on Jul. 12, 1983 and U.S. Pat. No. 4,436,234 issued to Kennedy on Mar. 13, 1984. In addition, U.S. Pat. No. 3,112,105 issued to Keller on Nov. 26, 1963 and U.S. Pat. No. 3,559,863 issued to Sack on Feb. 2, 1971 disclose devices for assembling furniture and U.S. Pat. No. 3,502,256 issued to Boulay et al. on Mar. 24, 1970 discloses an apparatus for closing and stapling cartons.
None of these prior machines or methods provide a machine or method for consistently, quickly and accurately positioning casing in a proper position relative a door jamb assembly or pre-hung door assembly and automatically fastening the casing to the door jamb assembly or pre-hung door assembly. Furthermore, use of the prior machines or methods does not result in a high quality work product.
Thus, there still exists a need in the technology for a machine and method for attaching casing to a pre-hung door assembly, or other structural frame assembly, which is quick, efficient, accurate and results in a high quality work piece. The machines and methods of this invention fulfill this need, as discussed below.